Contact person: Senior Node.js Backend Engineer – Fix Timezone-Based Push Notifications (Firebase + OneSignal)

Phone:Show

Email:Show

Location: Sydney, Australia

Budget: Recommended by industry experts

Time to start: As soon as possible

Project description:
"We’re looking for a highly experienced Node.js backend engineer to help us resolve a critical issue with our notification system, which is built using Firebase, OneSignal, and cron jobs.

Our app has users across multiple time zones, and we need to send notifications at specific local times per user (for example, 8:00 AM in their own timezone). We’ve already implemented cron based logic and are using OneSignal to handle delivery, but the system isn’t firing reliably (for example, one day it fires, the next day it doesn’t).

We need someone who can:
• Review and debug our existing cron job logic and timezone handling
• Ensure notifications are scheduled and delivered at the correct local time for each user, regardless of region
• Verify and optimize our Firebase and OneSignal setup
• Help us get the system fully functional across all user locations

Tech Stack:
• Node.js (backend)
• Firebase (auth, Firestore, cloud functions)
• OneSignal (push notifications)
• Cron jobs (already in use)

You should have:
• Deep experience handling timezone based logic at scale
• Strong Firebase and OneSignal integration knowledge
• Ability to identify subtle bugs or misconfigurations in notification pipelines
• Clean, efficient backend coding practices
• Available immediately to jump in and solve this fast

This is a short, high priority job. We’re close to the finish line but need a precision fix from someone who has solved this kind of problem before.

If you’re able to help us get this over the line, there is definitely potential for ongoing collaboration as we continue to scale the product and expand our backend infrastructure.

During the interview process, we’ll be specifically assessing your experience with timezone based notification systems at scale. If you haven’t built something like this before, we kindly request that you don’t apply, as we will be able to identify real experience very quickly. This role requires precision and prior hands on implementation, not experimentation." (client-provided description)